File storage service system, file management device, file management method, ID denotative NAS server and file reading method

ABSTRACT

The present invention relates to a migration of a file from a path denotative NAS server to an ID denotative NAS server. In a file management device  4 , a migration-use path denotative NAS access section  43  obtains a file deposit location from the path denotative NAS server  1 , selects a migration target file based on the deposit location, and sends a read request with the deposit location of the migration target file to the path denotative NAS server  1 , so as to obtain the migration target file. A migration-use denotative NAS access section  44  generates a write request with the migration target file, sends it to the ID denotative NAS servers  21, 22 , and writes the file therein. In addition, the migration-use ID denotative NAS access section  44  registers a GUID received from the ID denotative NAS servers  21, 22 , in a file name/GUID management table  45 , together with the file name of the migration target file.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a file storage service system,comprising a path denotative NAS server and an ID denotative NAS server.In particular, it relates to a technique to allow a file in the pathdenotative NAS server to migrate into the ID denotative NAS server, anda technique to access a file in the path denotative NAS server from anID denotative NAS client.

[0002] An NAS (Network Attached Storage) system is known as a filestorage service system of a client/server type. In the NAS system, whenan NAS server receives an access request from an NAS client via anetwork such as WAN and LAN, the NAS server performs a process accordingto the requested contents (write/read). In other words, when the NASserver receives from the NAS client a write request with a file, the NASserver writes the file into a disk device of its own server and retainsthe file. When the NAS server receives from the NAS client a readrequest with a denotation of file, the NAS server reads out the denotedfile from the disk device of its own server, and sends the file to theNAS client.

[0003] In the meantime, in the aforementioned NAS server, a denotationof a file received from the NAS client is performed based on a depositlocation of the file. The deposit location of the file comprises a nodename and a file path name, such as“hitachi.co.jp/usr/home/foobar/doc/memo.txt”. Here, “hitachi.co.jp”corresponds to the node name, and “/usr/home/foobar/doc/memo.txt”corresponds to the file path name. Hereinafter, in the presentspecification, the NAS server and the NAS client of a type in which thefile denotation is performed based on the file deposit location will bereferred to as a path denotative NAS server and a path denotative NASclient. As the path denotative NAS server, there are an NFS (NetworkFile System) server, a CIFS (Common Internet File System) server, or thelike. Furthermore, there are documents of prior art describing the pathdenotative NAS server, “UNIX Internals: The New Frontiers”, authored byUresh Vahalia, translated by Hideyuki Tokuda, Akira Nakamura, Yoshito Tobe, and Yoshiyuki Tsuda, issued by PEARSON Education, May 2000”, and“NFS illustrated” authored by Brent Callaghan, translated by QUIPUCorporation, issued by ASCII Corporation, Sep. 20, 2001.

[0004] Recently, a file storage service system, called as a distributedparallel NAS system, has been suggested. In the distributed parallel NASsystem, a file is divided into fragments and they are stored in aplurality of NAS servers in a distributed manner. Therefore, it has beenfound difficult for the NAS client to perform the file denotation basedon the file deposit location, since it is necessary for the NAS clientside to grasp all the deposit locations for every fragment. Then, inmany of the distributed parallel NAS systems, the NAS server handles thefile denotation received from the NAS client, based on a file identifiercalled as GUID (Global Unique Identifier). When the NAS server receivesa write request with a file from the NAS client, the NAS server dividesthe file into a plurality of fragments, and stores the fragments in aplurality of NAS servers including its own server in a distributedmanner. In addition, the NAS server generates a GUID of the file,notifies the NAS client of the GUID thus generated, and manages each ofthe deposit locations of the fragments in association with the GUID.When the NAS server receives from the NAS client a read request with adenotation of the GUID, the NAS server specifies a plurality of depositlocations being associated with the denoted GUID, restores the file byreading out the fragments respectively from the specified depositlocations, and sends the restored file to the NAS client. As the GUID,for example, a hash value of the file contents is used. The GUID and amethod for converting the GUID into file deposit locations are describedin “Distributed Content Location for Ubiquitous Environments” authoredby Kiyohide Nakauchi, Hiroyuki Morikawa, and Tomonori Aoyama, TechnicalReport of the Institute of Electronics, Information and CommunicationEngineers, NS2002-110 IN2002 CS2002, September 2002.

[0005] Hereinafter in the present specification, an NAS server and anNAS client of a type in which a file denotation is performed based onthe GUID, will be referred to as ID denotative NAS server and IDdenotative NAS client. As the ID denotative NAS server, there are “TheOceanStore Project” operated by University of California BerkeleyComputer Science Division in the U.S, and “PASIS” operated by CarnegieMellon University in the U.S. As documents of prior art by “TheOceanStore Project”, there are “The OceanStore Project ProvidingGlobal-Scale Persistent Data”, UC Berkeley Computer Science Division[online] [retrieved on Mar. 1, 2003], Internet <URL:http://oceanstore.cs.berkeley.edu/>, and “Maintenance-Free Global DataStorage” appears in IEEE Internet Computing Vol. 5, No. 5September/October 2001, pp. 40-49, authored by Sean Rhea, Chris Wells,Patrick Eaton, Dennis Geels, Ben Zhao, Hakim Weatherspoon, and JohnKubiatowicz. As documents of prior art by “PASIS”, there are “PASISEngineering Survivable Storage”, Carnegie Mellon University [online][retrieved Mar. 1, 2003] Internet <URL:http://www.pdl.cmu.edu/Pasis/index.html>, and “Survivable informationstorage systems” IEEE Computer 33(8) 61-68, August 2000, authored by JayJ. Wylie, Michael W. Bigrigg, John D. Strunk, Gregory R. Ganger, HanKiliccote, and Pradeep K. Khosla.

SUMMARY OF THE INVENTION

[0006] When an ID denotative NAS server is newly installed in additionto a path denotative NAS server already in operation, a demand from auser is expected that a file managed by the path denotative NAS serveraccessed from the ID denotative NAS client, by integrating the bothservers.

[0007] However, as described above, a method of reception of the filedenotation from the NAS client is different between the ID denotativeNAS server and the path denotative NAS server. Therefore, a file withinthe path denotative NAS server cannot be copied as it is into the IDdenotative NAS server. Furthermore, it is not possible for the IDdenotative NAS client to access a file in the path denotative NASserver.

[0008] The present invention has been made in view of the abovesituation, and an object of the present invention is to provide atechnique to allow a file in the path denotative NAS server to migrateinto the ID denotative NAS server. Another object of the presentinvention is to provide a technique to access a file within the pathdenotative NAS server from the ID denotative NAS client.

[0009] In order to solve the above problems, one aspect of the filestorage service system of the present invention comprises a pathdenotative NAS server which is an NAS server to perform a reception of afile denotation from a client based on a file deposit location, an IDdenotative NAS server which is an NAS server to perform the reception ofthe file denotation from the client based on a file identifier, and afile management device.

[0010] Here, the file management device comprises a path denotative NASaccess unit which sends a read request with a file deposit location tothe path denotative NAS server and reads a file from the path denotativeNAS server, an ID denotative NAS access unit which sends a write requestwith the file obtained by the path denotative NAS access unit to the IDdenotative NAS server to writes the file into the ID denotative NASserver, and receives from the ID denotative NAS server a file identifierof the file generated by the ID denotative NAS server, and a fileidentifier storing unit which stores information relating to the fileobtained by the path denotative NAS access unit, and the file identifierof the file obtained by the ID denotative NAS access unit in such amanner as associated with each other.

[0011] Alternatively, the file management device comprises a pathdenotative NAS access unit which sends a read request with a filedeposit location to the path denotative NAS server and reads a file fromthe path denotative NAS server, a file identifier generating unit whichgenerates a file identifier of the file obtained by the path denotativeNAS access unit, a file identifier registration requesting unit whichsends a file identifier registration request with the file depositlocation of the file obtained by the path denotative NAS access unit andthe file identifier of the file generated by the file identifiergenerating unit, and registers the file identifier in the ID denotativeNAS server in association with the file deposit location, and a fileidentifier storing unit which stores the information relating to thefile obtained by the path denotative NAS access unit and the fileidentifier of the file generated by the file identifier generating unitin such a manner as being associated with each other.

[0012] If the file management device corresponds to the latter case,when the file deposit location corresponding to the file identifierreceived from the client with the read request exists within the pathdenotative NAS server, the ID denotative NAS server sends the readrequest with the file deposit location to the path denotative NASserver, reads a file from the path denotative NAS server and sends thetile to the client.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a schematic diagram of a file storage service system towhich the first embodiment of the present invention is applied.

[0014]FIG. 2 is an illustration showing an example of registeredcontents in a GUID/positional information conversion table 25.

[0015]FIG. 3 is an illustration showing an example of registeredcontents in a file name/GUID management table ˜45.

[0016]FIG. 4 is a diagram showing an example of hardware configurationof the file storage service system as shown in FIG. 1.

[0017]FIG. 5 is a flow diagram to explain an operation of file migrationof the file management device 4.

[0018]FIG. 6 is a schematic diagram of a file storage service system towhich the second embodiment of the present invention is applied.

[0019]FIG. 7 is a flow diagram to explain an operation of ID registeringoperation of the file management device 4.

[0020]FIG. 8 is a flow diagram to explain a file reading operation ofthe TD denotative NAS servers 2 ₁, 2 ₂.

[0021]FIG. 9 is a schematic diagram of the file storage service systemto which the third embodiment of the present invention is applied.

[0022]FIG. 10 is a schematic diagram of the file storage service systemto which the fourth embodiment of the present invention is applied.

[0023]FIG. 11 is a flow diagram to explain an operation (instructionreceiving process) of a user terminal 6.

[0024]FIG. 12 is an illustration showing an example of a file depositlocation tree-structured diagram, which is displayed on the userterminal 6.

[0025]FIG. 13 is an illustration showing an example of a file attributedisplay screen, which is displayed on the user terminal 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereafter, preferred embodiments of the present invention will beexplained.

[0027] Firstly, the first embodiment of the present invention will beexplained.

[0028]FIG. 1 is a schematic diagram of a file storage service system towhich the first embodiment of the present invention is applied. As shownin the FIG. 1, a path denotative NAS server 1, ID denotative NAS servers2 ₁, 2 ₂, an ID denotative NAS client 3 and a file management device 4are configured, being connected to each other via a network 5 such asWAN and LAN.

[0029] The path denotative NAS server 1 is, as described in Backgroundof the Invention, an NAS server that receives a file denotation from aNAS client, based on a denotation of a file deposit location. As shownin FIG. 1, the path denotative NAS server 1 comprises a network IF(interface) section 11 which connects to the network 5, a storage deviceIF section 12 which connects to a storage device 18, an access receptor13 which handles an access request from the path denotative NAS client,and carries out reading/writing of a file from/to the storage device 18,and a positional information management table 14 which registers andmanages deposit location information (e.g., a directory structureinformation) of each file stored in the storage device 18.

[0030] When the access receptor 13 receives a request for file depositlocation information via the network IF section 11, it reads from thepositional information management table 14 the deposit locationinformation of each file stored in the storage device 18, and sends thusreadout deposit location information to a sending source of the requestfor file deposit location information.

[0031] When the access receptor 13 receives a write request with a fileand a denotation of the file deposit location, via the network IFsection 11, it access the storage device 18 via the storage device IFsection 12, and writes the file received with the write request to thefile deposit location as denoted. Furthermore, the access receptor 13adds the deposit location information of this file in the positionalinformation management table 14.

[0032] When the access receptor 13 receives a read request with adenotation of the file deposit location via the network IF section 11,it accesses the storage device 18 via the storage device IF section 12,and reads out the file stored in the file deposit location as denoted.Then, the access receptor 13 sends via the network IF section 11 thefile thus read out, to the sending source of the read request.

[0033] The ID denotative NAS servers 2 ₁, 2 ₂ are, as described inBackground of the Invention, NAS servers which receive a file denotationfrom the NAS client based on a denotation of GUID. As shown in FIG. 1,each of those ID denotative NAS servers comprises a network IF section21 which connects to the network 5, a storage device IF section 22 whichconnects to the storage device 28 for storing a file, such as HDD, anaccess receptor 23 which handles an access request from the IDdenotative NAS client and reads/writes a file to/from the storagedevices 28 of its own server and another ID denotative NAS server, aGUID generator 24 which generates a GUID to be given to the file, and aGUID/positional information conversion table 25 which is a table forregistering and managing a correspondence between the GUID and thedeposit location information of each fragment of the file to which theGUID has been given.

[0034]FIG. 2 is an illustration showing an example of registeredcontents of the GUID/positional information conversion table 25. Asshown in FIG. 2, the GUID 251 and the file deposit location 252 of thefile, which is given the GUID 251, are associated with each other andregistered in the GUID/positional information conversion table 25. Thefile deposit location 252 comprises a node name (for example, an IPaddress) 253 for specifying a node, and a file path name 254. In theexample as shown in FIG. 1, the node indicates either ID denotative NASserver 2 ₁ or the ID denotative NAS server 2 ₂. The file depositlocation 252 is denoted for each of the fragments of the file, beingstored in distributed manner. In the example as shown in FIG. 2, thefile which is given the GUID “0x00′0000′0000′0000′0000” is divided intofour fragments, and it is indicated that those four fragments are storedin distributed manner, respectively with

[0035] the node names “192.168.0.1”+file path name“/dist/0x0000′0000′/0000′0000′0000′0000′0001”,

[0036] node name “192.168.0.1”+file path name“/dist/0x0000′0000′/0000′0000′0000′0000′0002”,

[0037] node name “192.168.0.21”+file path name“/dist/0x0000′0000′/0000′0000′0000′0000′0003”,

[0038] node name “192.168.0.2”+file path name“/dist/0x0000′0000′/0000′0000′0000′0000′0004”.

[0039] When the access receptor 23 receives a write request with a filevia the network IF section 21, it allows the GUID generator 24 togenerate a GUID to be given to the file. In addition, the accessreceptor 23 divides the file into a plurality of fragments, and writeseach fragment in the storage device 28 connected to the storage deviceIF section 22 and/or the storage device 28 connected to another IDdenotative NAS server. Then, the access receptor 23 registers thedeposit location of each fragment in the GUID/positional informationconversion table 25, in association with the GUID, and sends the GUID tothe sending source of the write request via the network IF section 21.

[0040] When the access receptor 23 of one of the ID denotative NASservers 2 ₁, 2 ₂ writes a fragment to the storage device 28, which isconnected to the other of the ID denotative NAS servers 2 ₁, 2 ₁, theaccess receptor 23 of the one of the ID denotative NAS server 2 ₁, 2 ₂,for example, sends to the other of the ID denotative NAS servers 2 ₁, 2₂ in the other end, a write request with a fragment and a denotation ofa deposit location of the fragment. In receipt of the write request thussent, the access receptor 23 of the other of the ID denotative NASservers 2 ₁, 2 ₂, accesses the storage device 28 connected to its ownserver and stores in the deposit location thus denoted the fragmentreceived with the write request.

[0041] When the access receptor 23 receives a read request with adenotation of a GUID via the network IF section 21, it refers to theGUID/positional information conversion table 25, and specifies a depositlocation of each fragment of the file which is given the specified GUID.Then, it accesses the storage device 28 connected to the storage deviceIF section 22 and/or the storage device 28 connected to another IDdenotative NAS server, reads the fragments based on each depositlocation thus specified, so as to restore the file, and sends thusrestored file to the sending source of the read request.

[0042] When the access receptor 23 of one of the ID denotative NASservers 2 ₁, 2 ₂ reads the fragment from the storage device 28 connectedto the other of the ID denotative NAS servers 2 ₁, 2 ₂, the accessreceptor 23 of the one of the ID denotative NAS server 2 ₁, 2 ₂ sends aread request with a denotation of fragment deposit location to the otherof the ID denotative NAS server 2 ₁, 2 ₂. In receipt of this readrequest, the access receptor 23 of the other of the ID denotative NASserver 2 ₁, 2 ₂ accesses the storage device 28 connected to its ownserver, reads the fragment from the denoted deposit location, and sendsthe fragment to the one of the ID denotative NAS server 2 ₁, 2 ₂.

[0043] The ID denotative NAS client 3 has a function to obtain from thefile management device 4 that will be described below, a GUID of a filewhose deposit location has migrated from the path denotative NAS server1 to the ID denotative NAS servers 2 ₁, 2 ₂, in addition to a functionas a client of the ID denotative NAS servers 2 ₁, 2 ₂. As shown in FIG.1, the ID denotative NAS client 3 comprises a network IF section 31which connects to the network 5, a user IF section 32 which receives aninstruction from a user and displays file contents, an ID denotative NASaccess section 33 which requests reading/writing of files from/to the IDdenotative NAS servers 2 ₁, 2 ₂, and a file management device accesssection 34 which requests the file management device 4 to provide aGUID.

[0044] When the ID denotative NAS access section 33, for example,receives the GUID from a user via the user IF section 32, it generates aread request with the GUID, and sends the read request to either of IDdenotative NAS servers 2 ₁, 2 ₂, via the network IF section 31. Then,The ID denotative NAS access section 33 receives a file which is giventhe GUID from either of the ID denotative NAS servers 2 ₁, 2 ₂ anddisplays the file to user via the user IF section 32.

[0045] When the file management access section 34, for example, receivesa GUID acquisition instruction from a user via the user IF section 32,it generates a GUID acquisition request and sends the request to thefile management device 4 via the network IF section 31. Then, the filemanagement device access section 34 receives from the file managementdevice 4 a GUID of each file having migrated from the path denotativeNAS server 1 to the ID denotative NAS servers 2 ₁, 2 ₂, and displays thereceived GUID to the user via the user IF section 32.

[0046] The file management device 4 has a function as a client of thepath denotative NAS server 1, as well as a function as a client of theID denotative NAS servers 2 ₁, 2 ₂, and it allows a file depositlocation to migrate from the path denotative NAS server 1 to the IDdenotative NAS servers 2 ₁, 2 ₂. In addition, the file management device4 notifies the ID denotative client 3 of a GUID of a file, the depositlocation of which has migrated from the path denotative NAS server 1 tothe ID denotative NAS servers 2 ₁, 2 ₂. As shown in FIG. 1, the filemanagement device 4 comprises a network IF section 41 which connects tothe network 5, a user IF section 42 which receives an instruction from auser, a migration-use path denotative NAS access section 43 whichrequests the path denotative NAS server 1 to retrieve and read out afile, a migration-use ID denotative NAS access section 44 which requeststhe ID denotative NAS servers 2 ₁, 2 ₂ to write a file, a file name/GUIDmanagement table 45 which registers and manages a correspondence betweena file name and a GUID of the file, and a client request receptor 46which notifies the ID denotative client 3 of the registered contents ofthe file name/GUID management table 45, according to the GUIDacquisition request from the ID denotative client 3.

[0047]FIG. 3 is an illustration showing an example of registeredcontents of the file name/GUID management table 45. As illustrated, afile name 451 of a file and a GUID 452 given to the file, are registeredin the file name/GUID management table 45, in such a manner asassociated with each other. The example as shown in FIG. 3 indicatesthat the GUID of a file with the file name “proceeding_vo11_no1” is“0x00′0000′0000′0000′0000”, and the GUID of a file with the file name“memo” is “0x00′0000′0000′1111′0000”.

[0048]FIG. 4 is a diagram showing an example of hardware configurationof the file storage service system as indicated in FIG. 1. As shown inFIG. 4, a functional configuration of the path denotative NAS server 1as shown in FIG. 1 is implemented by allowing a CPU 71 to execute apredetermined program (a program for the path denotative NAS server)stored in a memory 72, in a computer system comprising the CPU 71, thememory 72, an NIC (Network Interface Card) 73 which connects to thenetwork 5, an HBA (Host Bus Adapter) 74 which connects to the storagedevice 18, and a bus 75 which connects each of those devices. In thisimplementation, the memory 72 is used for the positional informationmanagement table 14. A functional configuration of the ID denotative NASservers 2 ₁, 2 ₂ as shown in FIG. 1 is implemented by allowing a CPU 71to execute a predetermined program (a program for the ID denotative NASserver) stored in a memory 72 in a computer system having a similarconfiguration as that of the path denotative NAS server 1. In thisimplementation, the memory 72 is used for the GUID/positionalinformation conversion table 25.

[0049] A functional configuration of the ID denotative NAS client 3 asshown in FIG. 1 is implemented by allowing a CPU 71 to execute apredetermined program (a program for the ID denotative NAS client and aprogram for accessing the file management device) stored in a memory 72,in a computer system comprising the CPU 71, the memory 72, an NIC 73, anI/O device 76 such as a display and a keyboard, and a bus 75 whichconnects those devices above. A functional configuration of the filemanagement device 4 as shown in FIG. 1 is implemented by allowing a CPU71 to execute a predetermined program (a program for the file managementdevice) stored in a memory 72, in a computer system having a similarconfiguration as that of the ID denotative NAS client 3. In thisimplementation, a memory 72 is used for the file name/GUID managementtable 45.

[0050] Next, in the file storage service system with the aboveconfiguration, an operation for the file management device 4 to migratea file within the path denotative NAS server 1 to migrate into the IDdenotative NAS servers 2 ₁, 2 ₂, (referred to as a file migratingoperation.) will be explained. Hereinafter, this operation will bereferred to as a file migrating operation. FIG. 5 is a flow diagram forexplaining the file migrating operation of the file management device 4.This flow starts when the user IF section 42 receives a file migratinginstruction from a user.

[0051] Firstly, the migration-use path denotative NAS access section 43generates a request for file deposit location information, and sends itto the path denotative NAS server 1 via the network IF section 41. Then,the migration-use path denotative NAS access section 43 obtains from thepath denotative NAS server 1, deposit location information of each filewithin the path denotative NAS server 1 (S1001).

[0052] Subsequently, the migration-use path denotative NAS accesssection 43 selects a migration target file, out of the files within thepath denotative server 1 which are specified based on the depositlocation information obtained from the path denotative NAS server 1.Then, the migration-use path denotative NAS access section 43 generatesa read request with the deposit location information of the selectedfile, sends the read request to the path denotative NAS server 1 via thenetwork IF section 41, and obtains the migration target file from thepath denotative NAS server 1 (S1002). Then, the migration-use pathdenotative NAS access section 43 passes the migration target file to amigration-use ID denotative NAS access section 44.

[0053] Subsequently, the migration-use ID denotative NAS access section44 adds a new record to the file name/GUID management table 45, andregisters a file name of the migration target file on the added record(S1003). The file name of the migration target file can be specified,based on the deposit location information of the migration target file,file attribute information added onto the migration target file itselfand the like.

[0054] Subsequently, the migration-use ID denotative NAS access section44 generates a write request with the migration target file, sends thewrite request to either of the ID denotative NAS servers 2 ₁, 2 ₂, andobtains a GUID given to the migration target file from the either of theID denotative NAS servers 2 ₁, 2 ₂ (S1004).

[0055] Subsequently, the migration-use ID denotative NAS access section44 registers the GUID of the migration target file which is obtained instep S1004, on the record which is added to the file name/GUIDmanagement table 45 in step S1003 (S1005). Then, the migration-use IDdenotative NAS access section 44 notifies the migration-use pathdenotative NAS access section 43 of a completion of the migratingprocess as to the migration target file.

[0056] When the migration-use path denotative NAS access section 43receives the notification of the completion of the migrating process asto the migration target file from the migration-use ID denotative NASaccess section 44, it is determined whether or not all the files withinthe path denotative NAS server 1, which are specified by the depositlocation information obtained from the path denotative NAS server 1, areselected as migration target files (S1006). If there is a file which isnot selected, a process returns to S1002 to select the file as amigration target file, then, the process continues. Alternatively, ifall the files within the path denotative NAS server 1 are selected asmigration target files, this flow is ended.

[0057] According to the process above, all the files within the pathdenotative NAS server 1 are stored in the ID denotative NAS servers 2 ₁,2 ₂, and GUIDs of these files are registered in the file name/GUIDmanagement table 45 of the file management device 4. As described above,the client request receptor 46 notifies the ID denotative client 3 ofthe registered contents of the file name/GUID management table 45,according to the GUID acquisition request from the ID denotative client3. Then, the ID denotative client 3 sends a read request with the GUIDthus obtained to the ID denotative NAS servers 2 ₁, 2 ₂, whereby the IDdenotative client 3 can read a file having migrated from the pathdenotative NAS server 1 to the ID denotative NAS servers 2 ₁, 2 ₂.According to the present embodiment of the invention, it is possible toperform a smooth migration of the files within the path denotative NASserver 1 to the ID denotative NAS servers 2 ₁, 2 ₂.

[0058] In the present embodiment of the invention, a function of thefile management device 4 may be held by the path denotative NAS server.In other words, in FIG. 4, the program for the file management deviceand the file name/GUID management table stored in the memory 72 of thefile management device 4 may be stored in the memory 72 of the pathdenotative NAS server 1, and the CPU 71 of the path denotative NASserver 1 may execute the programs for the file management device 4, sothat the path denotative NAS server 1 may carry out the processes thatis supposed to be executed by the file management device 4. In thiscase, it is unnecessary to separately provide the file management device4 from the path denotative NAS server.

[0059] Next, the second embodiment of the present invention will beexplained.

[0060] In the first embodiment above, a file itself within the pathdenotative NAS server 1 is written in the ID denotative NAS servers 2 ₁,2 ₂, whereby the ID denotative client 3 can access the file.Alternatively, in the second embodiment, the ID denotative client 3 canaccess the file without writing the file itself within the pathdenotative NAS server 1 to the ID denotative NAS servers 2 ₁, 2 ₂.

[0061]FIG. 6 is a schematic diagram of the file storage service system,to which the second embodiment of the present invention has beenapplied. As shown in FIG. 6, each of the devices comprising the filestorage service system of the second embodiment is similar to those ofthe first embodiment as shown in FIG. 1. However, a part of thefunctional configuration of the ID denotative NAS servers 2 ₁, 2 ₂, andthe file management device 4 is different from that of the firstembodiment. As for the hardware configuration of each device comprisingthe file storage service system of the second embodiment is similar tothat of the first embodiment as shown in FIG. 4.

[0062] The ID denotative NAS servers 2 ₁, 2 ₂ of the second embodimentare different from the ID denotative NA$ server 2 ₁, 2 ₂ of the firstembodiment in the point that an access receptor 23 a is provided insteadof the access receptor 23. The access receptor 23 a performs thefollowing processing in addition to the function of the access receptor23 of the first embodiment.

[0063] That is, when the access receptor 23 a receives from the filemanagement device 4 via the network IF section 21 a GUID registeringrequest with a GUID and file deposit location information, the accessreceptor 23 a adds a new record to the GUID/positional informationconversion table 25, and registers in this record, the GUID and filedeposit location information (node name+file path name) received withthe GUID registering request.

[0064] Further, the access receptor 23 a also has a function as a pathdenotative NAS client. When the file deposit location informationregistered in the GUID/positional information conversion table 25 inassociation with the GUID received with the read request from the IDdenotative NAS client 3, has a node name indicating the path denotativeNAS server 1, it generates a read request with this file depositlocation information, and sends the read request to the path denotativeNAS server 1. Then, the access receptor 23 a sends the file obtainedfrom the path denotative NAS server 1, to the ID denotative NAS client3.

[0065] The file management device 4 of the present embodiment isdifferent from the file management device 4 of the first embodiment inthe points that a migration-use path denotative NAS access section 43 aand ID migration-use ID denotative NAS access section 44 a are providedinstead of the migration-use path denotative NAS access section 43 andthe migration-use ID denotative NAS access section 44, and that a GUIDgenerator 47 for generating a GUID is newly provided.

[0066] The migration-use path denotative NAS access section 43 a passesa file read out from the path denotative NAS server 1, together with thedeposit location of the file in the path denotative NAS server 1, to theID migration-use ID denotative NAS access section 44 a.

[0067] The ID migration-use ID denotative NAS access section 44 a allowsthe GUID generator 47 to generate a GUID of the file which is receivedfrom the migration-use path denotative NAS access section 43 a. Then,the ID migration-use ID denotative NAS access section 44 a registers theGUID generated by the GUID generator 47 in the file name/GUID managementtable 45, together with a file name of the file received from themigration-use path denotative NAS access section 43 a. In addition, theID migration-use ID denotative NAS access section 44 a generates a GUIDregistering request with the GUID generated by the GUID generator 47 andthe file deposit location information received from the migration-usepath denotative NAS access section 43 a, and sends the GUID registeringrequest to either of the ID denotative NAS servers 2 ₁, 2 ₂, via thenetwork IF section 41.

[0068] Subsequently, in the file storage service system with the aboveconfiguration, an operation for the ID denotative client 3 to be able toaccess a file within the path denotative NAS server 1, without writingthe file itself into the ID denotative NAS servers 2 ₁, 2 ₂, by the filemanagement device 4 (referred to as ID registering operation) will beexplained. FIG. 7 is a flow diagram to explain the ID registeringoperation of the file management device 4. This flow starts when theuser IF section 42 receives an ID registering instruction from a user.

[0069] Firstly, the migration-use path denotative NAS access section 43a obtains deposit location information of each file within the pathdenotative NAS server 1 in a similar manner as explained in steps S1001and S1002 of FIG. 5 (S2001). And the migration-use path denotative NASaccess section 43 a selects a migration target file among of the fileswithin the path denotative NAS server 1, the files being specified basedon the obtained deposit location information. Then, the migration-usepath denotative NAS access section 43 a sends a read request with thedeposit location information of the selected file to the path denotativeNAS server 1, and obtains the migration target file from the pathdenotative NAS server 1 (S2002). Further, the migration-use pathdenotative NAS access section 43 a passes the migration target file andthe deposit location information of the migration target file within thepath denotative NAS server 1 to the ID migration-use ID denotative NASaccess section 44 a.

[0070] Subsequently, the ID migration-use ID denotative NAS accesssection 44 a allows the GUID generator 47 to generate a GUID of themigration target file (S2003). Then, it adds a new record to the filename/GUID management table 45, and registers a file name of themigration target file and the GUID generated by the GUID generator 47(S2004).

[0071] Subsequently, the ID migration-use ID denotative NAS accesssection 44 a generates a GUID registering request with the GUID of themigration target file and the file deposit location information, andsends the GUID registering request to either of the ID denotative NASservers 2 ₁, 2 ₂ (S2005). As described above, in the ID denotative NASservers 2 ₁, 2 ₂, either of which received the GUID registering request,the access receptor 23 a adds a new record to the GUID/positionalinformation conversion table 25, and registers in this record the GUIDand the deposit location information (node name+file path name),received with the GUID registering request.

[0072] Subsequently, the ID migration-use ID denotative NAS accesssection 44 a notifies the migration-use path denotative NAS accesssection 43 a of a completion of the ID registering process as to themigration target file. When the migration-use path denotative NAS accesssection 43 a receives from the ID migration-use ID denotative NAS accesssection 44 a, the notification of the completion of the ID registeringprocess as to the migration target file, it determines whether or notall the files within the path denotative NAS server 1, which arespecified by the deposit location information obtained from the pathdenotative NAS server 1, are selected as migration target files (S2006).If there is a file not selected, the process returns to S2002 to selectthe file as a migration target file, then, the process continues.Alternatively, if all the files within the path denotative NAS server 1are selected as migration target files, the flow is ended.

[0073] According to the process above, GUIDs of all the files within thepath denotative NAS server 1 together with the file deposit locationinformation therein, are registered in the GUID/positional informationconversion table 25 of the ID denotative NAS servers 2 ₁, 2 ₂. Further,these GUIDs are registered in the file name/GUID management table 45 ofthe file management device 4. As described above, the client requestreceptor 46 notifies the ID denotative client 3 of the registeredcontents of the file name/GUID management table 45 according to the GUIDacquisition request from the ID denotative client 3. Then, the IDdenotative client 3 can read out a file within the path denotative NASserver 1, by sending to the ID denotative NAS servers 2 ₁, 2 ₂, a readrequest with the GUID obtained from the file management device 4.

[0074] Subsequently, in the file storage service system as configuredabove, a file reading operation of the ID denotative NAS servers 2 ₁, 2₂ will be explained.

[0075]FIG. 8 is a flow diagram to explain the file reading operation ofthe ID denotative NAS servers 2 ₁, 2 ₂. This flow starts when the accessreceptor 23 a receives a read request with a GUID, from the IDdenotative client 3 via the network IF section 21.

[0076] Firstly, the access receptor 23 a obtains deposit locationinformation corresponding to the GUID received with the read request, byuse of the GUID/positional information conversion table 25 (S3001).Here, if the GUID received with the read request is not registered inthe GUID/positional information conversion table 25 provided in its ownserver, the access receptor 23 a makes an inquiry to another IDdenotative NAS servers 2 ₁, 2 ₂, and obtains the deposit locationinformation corresponding to the GUID received with the read request,from the another ID denotative NAS servers 2 ₁, 2 ₂.

[0077] Subsequently, the access receptor 23 a determines whether or nota node name included in the obtained deposit location information (nodename+file path name) indicates the path denotative NAS server 1 (S3002).If the node name included in the deposit location information does notindicate the path denotative NAS server 1, that is, the node nameindicates the ID denotative NAS servers 21, 22, a normal operation as anID denotative NAS server is performed. And the access receptor 23 arestores a file by obtaining fragments respectively from the fragmentdeposit locations, which are specified by the deposit locationinformation (S3003). Whereby, the access receptor 23 a obtains the file.

[0078] Alternatively, if the node name included in the deposit locationinformation indicates the path denotative NAS server 1, the accessreceptor 23 a generates a read request with this deposit locationinformation, and sends the read request to the path denotative NASserver 1 via the network IF section 21 (S3004). Then, the accessreceptor 23 a obtains the file from the path denotative NAS server 1(S3005)

[0079] With the flow above, when the access receptor 23 a obtains thefile given the GUID received with the read request, it sends the filevia the network ID section 21 to the ID denotative NAS client 3 which isa sending source of the read request (S3006).

[0080] As described above, according to the present embodiment, it ispossible to access a file within the path denotative NAS server 1 fromthe ID denotative NAS client 3.

[0081] Next, the third embodiment of the present invention will beexplained.

[0082] In the first embodiment as described above, the file itselfwithin the path denotative NAS server 1 is written in the ID denotativeNAS servers 2 ₁, 2 ₂, whereby the ID denotative client 3 can access thefile. In the second embodiment above, the ID denotative client 3 canaccess the file without writing the file itself within the pathdenotative NAS server 1 into the ID denotative NAS servers 2 ₁, 2 ₂. Onthe other hand, the third embodiment is made to handle the both cases,i.e., the ID denotative client 3 can access the file by writing the fileitself within the path denotative NAS server 1 into the ID denotativeNAS servers 2 ₁, 2 ₂ (the first embodiment), and the ID denotativeclient 3 can access the file without writing the file itself within thepath denotative NAS server 1 into the ID denotative NAS servers 2 ₁, 2 ₂(the second embodiment).

[0083]FIG. 9 is a schematic diagram of the file storage service systemto which the third embodiment of the present invention is applied. Asshown in FIG. 9, each of the devices comprising the file storage servicesystem of the third embodiment is similar to those of the firstembodiment as shown in FIG. 1. However, a part of the functionalconfiguration of the ID denotative NAS servers 2 ₁, 2 ₂ and the filemanagement device 4 is different. As for the hardware configuration ofeach of the devices comprising the file storage service system of thethird embodiment, it is similar to that of the first embodiment as shownin FIG. 4.

[0084] The ID denotative NAS servers 2 ₁, 2 ₂ of the third embodimentare different from those in the first embodiment in the point that anaccess receptor 23 b is provided instead of the access receptor 23. Theaccess receptor 23 b performs the following process in addition to thefunctions of the access receptor 23 of the first embodiment and theaccess receptor 23 a of the second embodiment.

[0085] In other words, when the access receptor 23 b receives a GUIDdeletion request with the GUID from the file management device 4 via thenetwork IF section 21, the access receptor 23 b deletes the record withthe GUID from the GUID/positional information conversion table 25.

[0086] The file management device 4 of the third embodiment is differentfrom that of the first embodiment in the point that a migration-use pathdenotative NAS access section 43 b, a migration-use ID denotative NASaccess section 44 b are provided instead of the migration-use pathdenotative NAS access section 43 and the migration-use ID denotative NASaccess section 44, and the point that the ID migration-use ID denotativeNAS access section 44 a and he GUID generator 47 are newly provided,which are provided in the file management device 4 of the secondembodiment.

[0087] In the file storage service system with the configuration above,an ID registering operation of the file management device 4 is similarto that of the second embodiment as shown in FIG. 7. In addition, a filemigrating operation of the file management device 4 is similar to thatof the first embodiment as shown in FIG. 5, except the following points.That is, preceding the execution of S1001, the file management device 4generates a GUID deleting request with each GUID registered in the filename/GUID management table 45 and sends the GUID deleting request toeach of the ID denotative NAS servers 2 ₁, 2 ₂ via the network IFsection 41. The GUIDs registered by the ID registering operation arerespectively deleted from the GUID/positional information conversiontables 25 of the ID denotative NAS servers 2 ₁, 2 ₂. As well as a recordhaving each GUID which is requested to delete, is deleted from the filename/GUID management table 45. Then, the flow as shown in FIG. 5 isexecuted.

[0088] In general, the file migrating operation is accompanied with afile forwarding process from the file management device 4 to the IDdenotative NAS servers 2 ₁, 2 ₂ and a file writing process in the IDdenotative NAS servers 2 ₁, 2 ₂. Therefore, the file migrating operationtakes a longer period of time than the ID registering operation.According to the third embodiment, since the file management device 4performs the ID registering operation before the file migratingoperation, the ID denotative NAS client 3 can access a file, even beforethe completion of the file migrating operation as far as the IDregistering operation is completed.

[0089] Next, the fourth embodiment of the present invention will beexplained.

[0090]FIG. 10 is a schematic diagram of the file storage service systemto which the fourth embodiment of the is present invention is applied.As shown in FIG. 10, the file storage service system of the fourthembodiment has a configuration that a user terminal 6 is added to thefile storage service system of the third embodiment as shown in FIG. 9.

[0091] The user terminal 6 comprises a network IF section 61, a user IFsection 62, a file view generator 63 and an instruction generatingsection 64.

[0092] The file view generator 63 generates a file view screen forreceiving designation of a migration target file of the ID registeringoperation or the file migrating operation, by use of file depositlocation information registered in the positional information managementtable 14 of the path denotative NAS server 1, file attribute information(file name, creation date and time, file creator, file update person,file size and the like), which is given to the file itself stored in thestorage device 18 of the path denotative NAS server 1, and a GUIDregistered in the file name/GUID management table 45 of the filemanagement device 4, and the like. Then, the file view generator 63displays thus generated file view screen on a display via the user IFsection 62.

[0093] The instruction generating unit 64 generates an ID registeringinstruction or a file migrating instruction, with deposit locationinformation of the designated migration target file, according to theinstruction received from the user via the user IF section 62, and sendsthe instruction to the file management device 4 via the network IFsection 61.

[0094] The user terminal 6 as described above can also be implemented byallowing the CPU to execute a predetermined program stored in the memoryin a computer system having a similar configuration as that of the IDdenotative client 3.

[0095]FIG. 11 is a flow diagram to explain an operation (instructionreceiving process) of the user terminal 6. This flow starts when theuser IF section 62 receives from a user an instruction for displaying afile view.

[0096] Firstly, the file view generator 63 generates a file depositlocation information request, and sends the request to the pathdenotative NAS server 1 via the network IF section 61. Then, the fileview generator 63 obtains from the path denotative NAS server 1, thedeposit location information of each file within the path denotative NASserver 1 (S4001).

[0097] Subsequently, the file view generator 63 generates a fileattribute information request with the deposit location information ofeach file obtained in step S4001, and sends the request to the pathdenotative NAS server 1 via the network IF section 61. In the pathdenotative NAS server 1, when the access receptor 13 receives the fileattribute information request, it accesses the file deposit locationgiven the file attribute information request via the storage device IFsection 12, for example, and obtains the file attribute information heldby the file itself, which is registered at the deposit location.Alternatively, it obtains the file attribute information from the fileattribute management table which is not illustrated, where the fileattribute information is registered in association with the depositlocation. Then, the access receptor 13 sends the file attributeinformation thus obtained to the user terminal 6 via the network IFsection 11. The file view generator 63 obtains this file attributeinformation via the network IF section 61 (S4002).

[0098] Subsequently, the file view generator 63 generates a GUIDacquisition request and sends the request to the file management device4 via the network IF section 61. Then, the file view generator obtainseach GUID registered in the file name/GUID management table 45, togetherwith the file name, from the file management device 4 (S4003).

[0099] Then, the file view generator 63 generates a deposit locationtree-structured diagram (directory structure) within the path denotativeNAS server 1, based on the file deposit location information of eachfile obtained in step S4001, and displays the structure on the displayvia the user IF section 62 (S4004). FIG. 12 shows an example of the filedeposit location tree-structured diagram displayed on the user terminal6. In this example, it is indicated that four files,“proceeding_vo11_no1”, “memo”, “find”, and “who” are stored within thepath denotative NAS server 1, and two files “proceeding_vo11_no1” and“memo” are stored in a deposit location (directory)“/home/abc_committee/doc/”, and two other files “find” and “who” arestored in another deposit location (directory), “/usr/bin/”. A check box622 is provided to each file, and the user manipulates a cursor 621 toenter a check in a desired check box 622, so that a file can be selectedto display the file attribute information.

[0100] When the file view generator 63 receives from the user via theuser IF section 62, a file designation as to any of the files displayedin the file deposit location tree-structured diagram (S4005), itspecifies file attribute information of the designated file, out of thefile attribute information obtained in step S4002. Then, the file viewgenerator 63 generates a file attribute display screen for presentingthe user the specified file attribute information, and shows it via theuser IF section 62 on the display (S4006). Here, if the GUIDcorresponding to the file name of the designated file is included in theGUIDs obtained in step S4003, the GUID corresponding to the file name ofthe designated file is also included in the file attribute displayscreen. FIG. 13 shows an example of the file attribute display screendisplayed on the user terminal 6. In this example, the GUID of the fileis displayed together with the file attribute information, therefore,this file is accessible from the ID denotative NAS client 3. In FIG. 13,the reference number 623 indicates a button to receive an instructionfor returning to a screen of the file deposit location tree-structureddiagram on the display. The reference number 624 indicates a button toreceive an instruction for allowing the file management device 4 tocarry out an ID registering operation as to the displayed file, and thereference number 625 is a button to receive an instruction for allowingthe file management device 4 to carry out a file migrating operation asto the displayed file. The user manipulates the cursor 621 to select adesired button out of the buttons 623 to 625.

[0101] When the user IF section 62 receives an instruction from a userto display the file deposit location tree-structured diagram (“No” instep S4007, and “Yes” in step S4008), the user IF section 62 notifiesthe file view generator 63 of this instruction. In receipt of thisinstruction, the file view generator 63 displays the file depositlocation tree-structured diagram on the display by returning to stepS4004. In addition, when the user IF section 62 receives an instructionto allow the file management device 4 to carry out the ID registeringoperation or to carry out the file migrating operation as to the filedisplayed in the file attribute display screen (“Yes” in step S4007),the user IF section 62 notifies the instruction generating section 64 ofthis instruction. In receipt of this instruction, the instructiongenerating section 64 generates an ID registering instruction or a filemigrating instruction, together with the file name and the file depositlocation of the file displayed in the file attribute display screen, andsends the instruction to the file management device 4 via the network IFsection 61 (S4009).

[0102] In the file management device 4, when the migration-use pathdenotative NAS access section 43 b receives from the user terminal 6 theID registering instruction with the file name and the file depositlocation, it deletes a record including the file name from the filename/GUID management table 45. Then, a file specified by this file nameand the file deposit location is considered as a migration target file,and steps from S2002 to S2005 as shown in FIG. 7 are executed.

[0103] On the other hand, in the file management device 4, when themigration-use path denotative NAS access section 43 b receives from theuser terminal the file migrating instruction with the file name and thefile deposit location, it specifies a GUID corresponding to the filename from the file name/GUID management table 45. Then, themigration-use path denotative NAS access section 43 b generates a GUIDdeletion request with thus specified GUID, sends the request to each ofthe ID denotative NAS servers 2 ₁, 2 ₂ via the network IF section 41,and deletes the GUID thus specified respectively from theGUID/positional information conversion tables 25 of the ID denotativeservers 2 ₁, 2 ₂. And, the migration-use path denotative NAS accesssection 43 b deletes a record of thus specified GUID from the filename/GUID management table 45. Then, considering the file specified bythe file name and the file deposit location, as a migration target file,the steps from S1002 to S1005 as shown in FIG. 5 are executed.

[0104] According to the above embodiment, it is possible to carry outindividually, the ID registering operation and the file migratingoperation as to a file within the path denotative NAS server 1, which isdesignated by a user via the user terminal 6. In other words, the usercan selectively conduct a file migration, considering extinguish of thepath denotative NAS server 1, and a free space of the ID denotative NASservers 2 ₁, 2 ₂.

[0105] The present invention is not limited to each embodiment asdescribed above, and various changes and modifications may be possiblewithin the scope of the invention. For example, in each of the aboveembodiments, the number of devices comprising the file storage servicesystem is not necessarily limited to the number as shown in the figures.In addition, in each of the above embodiments, the file managementdevice 4 and the ID denotative NAS client 3 may be configured to be onone computer system. In addition, in each of the above embodiments,another file Identifier may be used instead of the GUID. In the fourthembodiment, the file management device 4, the ID denotative NAS client 3and the user terminal 6 may be configured on one computer system.Furthermore, the user terminal 6 of the fourth embodiment may beprovided in the file storage service system of the first embodiment orthe second embodiment.

[0106] As described above, according to the present invention, it ispossible to allow a file within the path denotative NAS server tomigrate into the ID denotative NAS server. In addition, it is alsopossible for the ID denotative NAS client to access the file within thepath denotative NAS server.

What is claimed is:
 1. A file storage service system comprising, a pathdenotative NAS server which is an NAS server to perform a reception of afile denotation from a client based on a file deposit location, an IDdenotative NAS server which is an NAS server to perform the reception ofthe file denotation from the client based on a file identifier, and afile management device, wherein, said file management device comprises,a path denotative NAS access unit which sends a read request with thefile deposit location to said path denotative NAS server, and reads afile from said path denotative NAS server, an ID denotative NAS accessunit which sends a write request with the file obtained by said pathdenotative NAS access unit to said ID denotative NAS server, and writesthe file into said ID denotative NAS server, as well as receiving fromsaid ID denotative NAS server, the file identifier of the file generatedby said ID denotative NAS server, and a file identifier storing unitwhich stores information relating to the file obtained by said pathdenotative NAS access unit, and the file identifier of the file obtainedby said ID denotative NAS access unit, in such a manner as theinformation and the file identifier being associated with each other. 2.A file storage service system according to claim 1, further comprising auser terminal, wherein, said user terminal comprises, a file informationdisplay unit which displays on a display device various information ofthe file within said path denotative NAS server, and an instruction unitwhich receives the file denotation to allow said file management deviceto read the file from said path denotative NAS server, and sends areading instruction with the file denotation to said file managementdevice, and said path denotative NAS access unit of said file managementdevice sends to said path denotative NAS server the read request withthe file deposit location of the file denoted by the reading instructionreceived from said user terminal.
 3. A file storage service systemcomprising, a path denotative NAS server which is an NAS server toperform a reception of a file denotation from a client based on a filedeposit location, an ID denotative NAS server which is an NAS server toperform the reception of the file denotation from the client based on afile identifier, and a file management device, wherein, said filemanagement device comprises, a path denotative NAS access unit whichsends a read request with the file deposit location to said pathdenotative NAS server, and reads a file from said path denotative NASserver, a file identifier generating unit which generates the fileidentifier of the file obtained by said path denotative NAS server, afile identifier registration requesting unit which sends a fileidentifier registration request with the file deposit location of thefile obtained by said path denotative NAS access unit and the fileidentifier of the file generated by said file identifier generatingunit, and registers the file identifier in said ID denotative NAS serverin association with the file deposit location, and a file identifierstoring unit which stores information relating to the file obtained bysaid path denotative NAS access unit and the file identifier of the filegenerated by said file identifier generating unit in such a manner asthe information and the file identifier being associated with eachother, wherein, when the file deposit location corresponding to the fileidentifier received with the read request from the client exists withinsaid path denotative NAS server, said ID denotative NAS server sends theread request with the file deposit location to said path denotative NASserver, reads a file from said path denotative NAS server, and sends thefile to the client.
 4. A file storage service system according to claim3, wherein, said file management device further comprises, an IDdenotative NAS access unit which sends a write request with the fileobtained by said path denotative NAS access unit to said ID denotativeNAS server, and writes the file into said ID denotative NAS server, aswell as receiving the file identifier of the file generated by said IDdenotative server from said ID denotative NAS server, and said fileidentifier storing unit stores information relating to the file obtainedby said path denotative NAS access unit, and the file identifier of thefile obtained by said ID denotative NAS access unit, in such a manner asthe information and the file identifier being associated with eachother.
 5. A file storage service system according to claim 3, furthercomprising a user terminal, wherein, said user terminal comprises, afile information display unit which displays on a display device variousinformation of the file within said path denotative NAS server, and aninstruction unit which receives the file denotation to allow said filemanagement device to read the file from said path denotative NAS server,and sends a reading instruction with the file denotation to said filemanagement device, wherein, said path denotative NAS access unit of saidfile management device sends to said path denotative NAS server the readrequest with the file deposit location of the file denoted by thereading instruction received from said user terminal.
 6. A filemanagement device that is employed with a connection via a network to apath denotative NAS server which is an NAS server to perform a receptionof a file denotation from a client based on a file deposit location, andan ID denotative NAS server which is an NAS server to perform thereception of the file denotation from the client based on a fileidentifier, comprising, a path denotative NAS access unit which sends aread request with the file deposit location to said path denotative NASserver and reads a file from said path denotative NAS server, an IDdenotative NAS access unit which sends a write request with the fileobtained by said path denotative NAS access unit to said ID denotativeNAS server, and writes the file into said ID denotative NAS server, aswell as receiving from said ID denotative NAS server, the fileidentifier of the file generated by said ID denotative NAS server, and afile identifier storing unit which stores information relating to thefile obtained by said path denotative NAS access unit, and the fileidentifier of the file obtained by said ID denotative NAS access unit,in such a manner as the information and the file identifier beingassociated with each other.
 7. A file management device being employedwith a connection via a network to a path denotative NAS server which isan NAS server to perform a reception of a file denotation from a clientbased on a file deposit location, and an ID denotative NAS server whichis an NAS server to perform the reception of the file denotation fromthe client based on a file identifier, comprising, a path denotative NASaccess unit which sends a read request with the file deposit location tosaid path denotative NAS server, and reads a file from said pathdenotative NAS server, a file identifier generating unit which generatesthe file identifier of the file obtained by said path denotative NASserver, a file identifier registration requesting unit which sends afile identifier registration request with the file deposit location ofthe file obtained by said path denotative NAS access unit and the fileidentifier of the file generated by said file identifier generatingunit, and registers the file identifier in said ID denotative NAS serverin association with the file deposit location, and a file identifierstoring unit which stores information relating to the file obtained bysaid path denotative NAS access unit and the file identifier of the filegenerated by said file identifier generating unit in such a manner asthe information and the file identifier being associated with eachother.
 8. A program which is readable by a computer, wherein, saidcomputer is employed with a connection via a network to a pathdenotative NAS server which is an NAS server to perform a reception of afile denotation from a client based on a file deposit location, and anID denotative NAS server which is an NAS server to perform the receptionof the file denotation from the client based on a file identifier,wherein, said program allows a system of said computer to function as, apath denotative NAS access unit which sends a read request with the filedeposit location to said path denotative NAS server, and reads a filefrom said path denotative NAS server, an ID denotative NAS access unitwhich sends a write request with the file obtained by said pathdenotative NAS access unit to said ID denotative NAS server, and writesthe file into said ID denotative NAS server, as well as receiving fromsaid ID denotative NAS server, the file identifier of the file generatedby said ID denotative NAS server, and a file identifier storing unitwhich stores information relating to the file obtained by said pathdenotative NAS access unit, and the file identifier of the file obtainedby said ID denotative NAS access unit, in such a manner as theinformation and the file identifier being associated with each other. 9.A program which is readable by a computer, wherein, said computer isemployed with a connection via a network to a path denotative NAS serverwhich is an NAS server to perform a reception of a file denotation froma client based on a file deposit location, and an ID denotative NASserver which is an NAS server to perform the reception of the filedenotation from the client based on a file identifier, wherein, saidprogram allows a system of said computer to function as, a pathdenotative NAS access unit which sends a read request with the filedeposit location to said path denotative NAS server, and reads a filefrom said path denotative NAS server, a file identifier generating unitwhich generates the file identifier of the file obtained by said pathdenotative NAS server, a file identifier registration requesting unitwhich sends a file identifier registration request with the file depositlocation of the file obtained by said path denotative NAS access unitand the file identifier of the file generated by said file identifiergenerating unit, and registers the file identifier in said ID denotativeNAS server in association with the file deposit location, and a fileidentifier storing unit which stores information relating to the fileobtained by said path denotative NAS access unit and the file identifierof the file generated by said file identifier generating unit in such amanner as the information and the file identifier being associated witheach other.
 10. A file management method employing a computer with aconnection via a network to a path denotative NAS server which is an NASserver to perform a reception of a file denotation from a client basedon a file deposit location, and an ID denotative NAS server which is anNAS server to perform the reception of the rile denotation from theclient based on a file identifier, wherein, said computer executes, areading step which sends a read request with the file deposit locationto said path denotative NAS server, and reads a file from said pathdenotative NAS server, a receiving step which sends a write request withthe file thus obtained to said ID denotative NAS server, writes the fileinto said ID denotative NAS server, as well as receiving from said IDdenotative NAS server the file identifier of the file generated by saidID denotative NAS server, and a storing step which stores in a storagedevice information relating to the file thus obtained and the fileidentifier of the file in such a manner as the information and the fileidentifier being associated with each other.
 11. A file managementmethod employing a computer, with a connection via a network to a pathdenotative NAS server which is an NAS server to perform a reception of afile denotation from a client based on a file deposit location, and anID denotative NAS server which is an NAS server to perform the receptionof the file denotation from the client based on a file identifier, saidfile management method executes, a reading step which sends a readrequest with the file deposit location to said path denotative NASserver and reads the file from said path denotative NAS server, agenerating step which generates the file identifier of the file thusobtained, a registering step which sends a file identifier registrationrequest with the file deposit location of the file thus obtained and thefile identifier of the file generated, and registers the file identifierin said ID denotative NAS server in association with the file depositlocation, and a storing step which stores in a storage device,information relating to the file thus obtained and the file identifierof the file generated, in such a manner as the information and the fileidentifier being associated with each other.
 12. An ID denotative NASserver which is an NAS server to perform a reception of a filedenotation from a client based on a file identifier, being employed witha connection via a network to a path denotative NAS server which is anNAS server to perform the reception of the file denotation from theclient based on a file deposit location, comprising, anidentifier/deposit location storing unit which stores by file, the fileidentifier and the file deposit location in such a manner as associatedwith each other, and an access receptor unit which reads a file, inaccordance with a read request with the file identifier received fromthe client, based on the file deposit location stored in saididentifier/deposit location storing unit, the file deposit locationcorresponding to the file identifier received with said read request,and sends the file thus read out to said client, wherein, when the filedeposit location stored in said identifier/deposit location storing unitbeing associated with the file identifier received with said readrequest exists in said path denotative NAS server, said access receptorunit sends the read request with the file deposit location to said pathdenotative NAS server, reads a file from said path denotative NASserver, and sends the file to said client.
 13. A program which isreadable by a computer, wherein, said computer is employed with aconnection via a network to a path denotative NAS server, which is anNAS server to perform a reception of a file denotation from a clientbased on a file deposit location; said program allows a system of saidcomputer to function as an ID denotative NAS server which is an NASserver to perform the reception of the file denotation from the clientbased on a file identifier; and when the file deposit locationcorresponding to the file identifier received from the client with theread request exists in said path denotative NAS server, said programallows to send a read request with the file deposit location to saidpath denotative NAS server, to read a file from said path denotative NASserver, and to send the file to said client.
 14. A file reading methodusing a computer that is employed with a connection via a network to apath denotative NAS server, which is an NAS server to perform areception of a file denotation from a client based on a file depositlocation, wherein said computer functions as an ID denotative NASserver, which is an NAS server to perform the reception of the filedenotation from the client based on a file identifier and executes, aconfirming step which confirms the file deposit location correspondingto the file identifier given to a read request received from the client,and a sending step which reads a file from the file deposit locationthus confirmed, and sends the file to the client, wherein, when the filedeposit location thus confirmed exists in said path denotative NASserver, said sending step sends the read request with the file depositlocation to said path denotative NAS server, reads the file from saidpath denotative NAS server and sends the file to said client.